Illuminated panel and method of fabricating same



Nov. 15, 1960 D. A. DETLoFF 2,959,880

ILLUMINATED PANEL AND METHOD OF FABRICATING SAME Filed June 30, 1954FUEL MANIFOLD /2 1111411 lll.

DONALD A. DETL Attorney.

United States Patent O ILLUIVIINATED PANEL AND METHOD F FABRICATING SAMEDonald Arthur Detloif, Van Nuys, Calif., assignor to CaliforniaPlasteck, Inc., Los Angeles, Calif., a corporation Filed .lune 30, 1954,Ser. No. 440,437

9 Claims. (Cl. 40-130) This invention relates to panels having designsthereon comprising such components as indicia, letters, numerals, andother markings, which designs are visible both by reflected light and bylight transmitted through the material of the panel. Transilluminatedpanels of this character are commonly used -for instrument boards andpanel boards on aircraft.

In general, a panel of the type to which the invention pertainscomprises a laminated plate having a relatively thick inner or backlayer of light-transmitting material suitable for transillumination andhaving an outer or front layer of opaque material which has cut-outsconforming to the desired design. In one construction, an intermediatelayer of light-reflecting translucent material underlies the outeropaque layer and this intermediate layer is exposed through the cut-outsto provide the design.

One prior art procedure for fabricating such a panel comprises the stepsof: bonding together three sheets of thermoplastic materialcorresponding to the desired three layers to -form a unified plate;applying heat `and pressure to `displace selected portions of the plateoutward to form a relief pattern; and shaving material from the reliefpattern to make cut-outs in the outer opaque layer and to expose theoutwardly displaced portions of the intermediate light-reflectingtranslucent layer. If all of the elements of the design are relativelynarrow, the result of this procedure is a well-defined clean-cut designformed by the material of the intermediate layer as exposed through thecut-outs of the outer opaque layer. For exlample, a design consistingsolely of such elements as narrow index marks, scale marks, relativelysmall letters and relatively small numerals, will have the desiredsharpness of definition.

It has been found, however, that this prior 'art procedure does notproduce satisfactory designs when the design elements are relativelywide. Since the nished design is formed by removing the relief portions,the finished design boundaries are formed by the intersection of theoutwardly offset portions of the opaque layer with the plane to whichthe relief design is cut back by removal of material and such a line ofintersection inevitably wavers along the edge of a wide design area. Thewavering line of demarcation arises from the fact that in the process offorming the relief design, the material of the intermediate layer failsto flow outward uniformly in response to the applied heat and pressurein regions along the edges of wide design areas.

It is also difficult to control the thickness of the intermediate layerthat remains when the relief pattern is shaved to create a wide portionof a design. The intermediate layer is not displaced outwardly with sucha `degree of precision and uniformity in the production of the reliefpattern as to make possible the shaving away of a uniform thickness ofthe intermediate layer over -a design area of any substantial width.

The invention meets this problem of sharply defining relatively widedesign areas by aording a diiferent pro- ICC cedure which involvescutting out portions of at least the outer opaque layer in accord withthe desired designr andy then applying an additional outer layer oflight-reiecting translucent material in accord with the design. Theelements of the applied outer layer are superimposed on thecorresponding elements of the cut-out dign and are wider than thecorresponding elements of the cut-out design so that the clean-cutmargins of the applied layer overlap` the margins of the cut-out designareas. As aresult, the margins of the cut-out areas are not visible whenthe design is viewed by reilected light and the diffusion of theVtransmitted light by the additional layer of translucent material makesirregularities in the edges of the cutout area unnoticeable when thedesign is viewed by transmitted light.

The new procedure -provides an added advantage in that it makes itpossible to provide desirably wide design areas' for easy visibility byreflected light, and -at the same time,

to provide desirably narrow design areas for illumination,

`by transmitted light. Thus the invention resolves a certain conflictbetween, on the one hand, the requirement for boldly depicted designareas for observation by rellectped` may be considered as actuallydivided into a rst design'.

having relatively wide `design elements and a second design havingrelatively narrow design elements. 'Ille first ,design is produced byproviding cut-out elements in the outer opaque layer and then applyingwider elements ,ofthe additional layer of light-reflecting translucentmaterial to overlap the cut-out elements by liberal margins. 'Ifhesecond design composed of the narrow design elements is produced byfirst forming -a corresponding relief design' and then shaving therelief design to cutout narrowpor-r tions of the opaque layer to exposecorresponding narrow portions of the intermediate translucent layer.

In one practice of the invention involvingtwo such designs, heat andpressure are applied to form two cor-' responding relief designs havingwide elements and narrow.

elements respectively. Material is then removed from both the reliefdesigns to provide the two required cut-out designs. The relief designfor the relatively narrowdesign elements protrudes by a relatively smalldimension sovthe' operation of shaving this design results in cut-outsin the. outer opaque layer but merely skims the intermediateVtranslucentrlayer so that the finished .design is ,inthe exposed areasof the intermediate layer. The otherreliefy design composed of the widerdesign elements protrudes by a greater dimension in this particularpractice of thef invention so that shaving of the second reliefdesigncuts out the intermediate translucent layer in addition to .the'

outer opaque layer.

In another practice of the invention/the design having wider designelements is produced by engraving the multiple-ply plate instead ofsubjecting the plate to'heatV and pressure for the production of arelief design. The engraving may be of relatively light depth topenetrate. to less than the full thickness of the intermediate trans-vlucent layer if desired.

the outer opaque layer and the intermediate translucent layer, and inaddition penetrates the lrelatively thick inneij` or back layer to for-mrecesses therein corresponding to" In the preferred practice of ftheinvention, however, the engraving extends through both,

the cut-out portions of the two outer layers. An important advantage ofrecessing the back plate in this manner is that the recesses providetransilluminated areas that increase the visibility of the design indarkness. The design is then completed by applying the additional layerof light-retiecting translucent material to cover and overlap thecut-outs for the wider design elements.

The features and advantages of the invention may be understood from thefollowing description considered with the accompanying drawing.

In the drawing, which is to be considered as merely illustrative:

Figure 1 is a fragmentary face view of a panel embodying one practice ofthe invention, portions of the two outer layers of the panel beingbroken away;

Figure 2 is a section taken as indicated by the line 2 2 of Figure 1showing a lamp mounted for transillurnination of the panel;

Figure 3 is a section taken as indicated by the line 3--3 of Figure 1;

Figure 4 is a section taken as indicated by the line 4-4 of Figure 1,showing how the design of relatively Wide elements may be created;

Figure 5 is a view similar to Figure 4 showing how the second design ofrelatively narrow elements may be produced; and

Figure 6 is a section similar to Figure 5, illustrating an alternatepractice of the invention for producing the design that has relativelywide elements.

The drawing shows by way of example, how the invention may be embodiedin a panel, generally designated by the letter P, which is employed asindicating means in conjunction with a fuel system on an aircraft. In afuel system represented by the panel, fuel is supplied to a fuelmanifold from a plurality of fuel `tanks or cells positioned atdifferent points on the aircraft and the route of fuel ow through thepiping of the system must be changed to switch from one fuel source toanother. The purpose of the panel P is -to indicate the state of thefuel system with respect to the adjustment of valves controlling theroute of the fuel flow. The panel P is transilluminated by a lamp bulb10 (Figure 2) in a lamp housing, generally designated by numeral 11(Figures 1 and 2), so that the design of markings on the outer face ofthe panel may be viewed either by reected light from external sources,or may be viewed by transillumination.

The markings on the face of the panel P include a relatively wide line14 representing the fuel manifold. Pipes connected to the fuel manifoldare represented on the panel by a broken line 15 and by continuous lines16, 17, 18, 19. A rotary disk incorporated in the panel constructionrepresents a 4-way valve in the fuel system and has a pair of spacedarcuate lines 22 and 23 thereon to represent paths of fuel ow Ithroughthe valve.

In the rotary position of the rotary disk 20 shown in Figure 1, the4-way valve represented by the disk connects the two pipes representedby lines 17 and v18 with a corresponding pair of pipes represented bylines 24 and 25 respectively. At the alternate position of the disk,rotated approximately 90 degrees clockwise from the position shown inFigure l, the arcuate line 22 on the disk interconnects lines 24 and 25and the arcuate line 23 interconnects lines 17 and 18 to indicate thecorresponding functional relationship between the pipes and the 4-Wayvalve at its alternate position.

The actual 4-way valve (not shown), that is represented Iby the rotarydisk 20, is controlled by a knob on the panel P. The knob 30 covers acircular aperture 31 in the panel P and may be made of any suitablematerial either translucent or opaque. The knob 30 is mounted on theouter end of an operating shaft 32 that controls the 4-way valve. Theoperating shaft 32 is reduced in diameter to provide a reduced endportion 33 andra radial shoulder 34. The reduced end portion 33 isthreaded to receive a suitable nut 35 which co-operates with the radialshoulder 34 to clamp a disk 36 on the operating shaft in a xed manner.

The disk 36, which may be made of suitable plastic material, has acircumferential groove to receive a suitable belt member 41 that engagesa similar circumferential groove 42 on the periphery of a second similardisk 43. It is apparent that the second disk 43 will rotate in unisonwith the knob 30. The second disk 43 is adapted to actuate thepreviously mentioned rotary panel disk 20 which represents the 4wayvalve actuated by the operating shaft 32.

As shown in Figure 3, the rotary panel disk 20, which is of the sameconstruction and material as the panel P, is rotatably mounted in acircular aperture 44 that is recessed to form an outwardly directedshoulder 45. The panel disk 20 is formed with a circumferential radialshoulder 46 which rests against the shoulder 45 to keep the panel diskfrom shifting in one axial direction. A thin circular plate 47, which isattached to the inner side of `the panel disk 20 prevents axial movementof the panel disk in the opposite direction. In the construction shown,a pin 50, having an outer head 51 extends through the panel disk 20 andthe circular plate 47 axially thereof and is threaded at its inner endto carry a pair of nuts 52 and 53. Nut 52 co-operates with the head 51of the pin to clamp the circular plate 47 against Y the inner side ofthe rotary disk 20 and the two nuts 52 and 53 cooperate to clamp thesecond peripherally grooved disk 43 on the pin 50.

At the positions of the knob 30 and the rotary panel disk 20 shown inFigure 1, a pointer 54, extending radially from the knob 30 and integraltherewith, is posi tioned at a rst index spot 55 on the panel P. At thealternate position of the rotary panel disk 20, and, of course, at thecorresponding alternate position of the 4- way valve represented by thepanel disk, the pointer 54 of the knob 30 registers with a second indexspot 56.

The lamp housing 11 may be of any suitable construction for the purpose.In the well-known construction shown in the drawing, the housingincludes a metal barrel 60 that is peripherally threaded to receive apair of thin nuts 61 that co-operate to clamp `the housing to the panelP with the housing extending through a circular aperture 62 in thepanel. The metal barrel 60 has a series of circumferentially spacedslots 63 positioned to direct light into the panel edgewise of theaperture 62 for transillumination of the panel. The base ferrule 64 ofthe lamp which forms one of its two contacts is embraced by an innermetal sleeve 65 which is electrically connected with one side of thelamp circuit and is insulated from the metal barrel 60 by a liner 66 ofsuitable conducting material. The metal sleeve 65 has circumferentiallyspaced windows 67 which register with the circumferentially spaced slots63 of the metal barrel 60 to permit light to escape from the housing.

The metal sleeve 65, which has a terminal portion 68 adapted forelectrical connection with the lamp circuit, serves to conne a suitablespring 69 that presses the lamp bulb 10 endwise to hold the end contact70 of the lamp bulb against a dished metal disk 71. The dished metaldisk 71 is pressed by a second stronger spiral spring 72 against the rimof the metal barrel 60. Thus the second contact 70 of the lamp bulb iselectrically connected with the lamp circuit through the dished metaldisk 71 and the metal barrel 60. The portion of the lamp housing thatextends forward or outward from the panel is covered by an opaqueplastic cap 73 that screws onto the metal barrel 60.

As heretofore indicated, the present invention is directed to theproblem of providing the overall design of markings on the panel P forobservation both by reflected light and by transillumination. Theinvention is especially directed to the problem of providing the designelements that are relatively wide, a different technique beingcontemplated for the wider design elements than for the relativelynarrow design elements. Thus in the application of -the invention to theconstruction of the panel P shown in Figure 1, the markings on the panelare consided as constituting two separate designs.

One of the two designs includes all of the relatively broad designelements and therefore comprises the following design elements shown inFigure 1: the line 14 representing the fuel manifold; the broken line 15branching from the manifold line; the continuous lines 16, 17, 18 and 19also branching from the manifold line; the two arcuate lines 22 and 23representing the flow passages through the 4-way valve; the two lines 24and 25 representing pipes connected to the 4-way valve; and the twoindex spots 55 and 56 associated with the knob 30.

The second of the two designs which is made up of narrow designelements, includes all the small lettering on the panel P, such as thelettering spelling out fuel manifold. This second design also includessuch elements as the small rectangle 74 and the small arrows 75 thereinwhich indicate directions of flow through various pipes such as thepipes represented by the lines 16 and 19.

One construction and method of fabrication suitable for providing the`first design of relatively broad design elements may be understood byreferring to Figure 4.

lThe panel P, shown in cross-section in Figure 4, comprises a 3-plylaminated plate. The base lamination is a relatively thick layer 80 ofsuitable light-transmitting or semitransparent plastic material such asmethyl methacrylate which is commonly sold under the trade namesPlexiglas and Lucite. Bonded to this inner or back layer 80 is anintermediate relatively thin layer 81 of suitable light-reliectingtranslucent material and bonded, in turn, to the intermediate layer 81is an outer or front relatively thin layer 82 of opaque material. Bothof these layers 81 and 82 may be made essentially of a vinyl orpolyvinyl resin such as polyvinyl chloride with suitable plasticizersincluded. Thus, the 3-ply laminated plate that forms the body of thepanel P is made entirely of thermoplastic material in the preferredpractice of the invention. Since all of the Ithree layers arethermoplastic, the three layers may be bonded together simply by theapplication of heat and pressure in a manner well-known in the art.

The design comprising the relatively wide design eiements may beprovided by first engraving the 3-ply plate with the pattern ofengraving conforming to the desired design, but with the engraved linemuch narrower than the lines that are desired to be visible by reflectedlight. Thus, as shown in Figure l, relatively narrow lines are engravedon the outer side of the 3-ply plate and as shown in Figure 4, theengraving not only extends through the outer or front layer 82 and theintermediate layer 81, but also penetrates the inner or back layer.Thus, the engraving results in relatively narrow slots or cut-outs 83 inthe outer layer 82, corresponding cut-outs 84 in register therewith inthe intermediate layer 81, and finally corresponding recesses 85 in -theback layer 80 in register with the cut-outs.

It is the cut-outs 83 and 84, together with the recesses 85, that permittransillumination of the wider design elements. It is not necessary forthe engraving to penetrate completely through the intermediate layer 81,but such penetration is desirable because the resulting recesses 85extend into the interior of the back layer 82 and the bottom corners 86of the recesses are illuminated by the lamp bulb 10, -to make thecorresponding design marks visible by transillumination. Preferably, thecorners 86 are rounded as shown to produce a desirable optical effect.

The next step for providing the relatively broad elements of the firstdesign is to apply an additional layer 90 of suitable translucentmaterial to cover the cut-outs and recesses. The additional layer 90extends laterally both directions from the cut-outs to provide the widthof the design elements desired for clear visibility byreliected light.Thus, as shown in'Figures 1 and 4, the additional layer 90 issubstantially wider than the cutouts and recesses to provide the desiredrelatively broad design elements. The particular additional layer 90that is shown in Figure 4 provides the broad mark 25 of Figure 1.

This layer 90 of additional light-reflecting translucent material isshown in Figure 4 as completely filling the groove provided by thecut-outs 83 and 84 together with the corresponding recess 85, but theadditional layer need not completely ll the groove. The additional layer90 may comprise ordinary white paint, if desired, or may comprise anytranslucent mixture of plastic material or other material. If a numberof panels are to be produced, the additional layer 90 may be applied toeach panel by a stencil technique.

Since the application of the additional layer 90 may be easilycontrolled within close dimensions, it is a simple matter to form thevarious relatively wide design elements with clean-cut well-definededges. The engraving also provides clean-cut demarcations, but since theareas that are lighted by transillumination are relatively narrow,clean-cut demarcation of the cut-outs 83 and 84 and the recesses 85 isnot important, especially because the additional translucent layerdiffuses the transmitted light.

The second design made up of relatively narrow design elements may beprovided by a well-known technique illustrated by Figure 5. In thistechnique which is set forth at length in the Sullivan Patent 2,602,036,the 3-ply thermoplastic plate is subjected to heat and pressure in asuitable mold that causes viscous ow of the three lamina-V The degree ofoutward protrusion of the two layers 482` and 81 to form the reliefpattern is such then when thef relief pattern is shaved away, a gap orcut-out 92. is formed in the outer opaque layer 82, to expose theintermediate light-reflecting translucent layer 81. Preferably, theprotrusion in making the relief pattern is of such degree that only aportion of the intermediate layer isV skimmed off when the reliefpattern is removed, the result being shown in Figure 5. If desired,however, a gap or cut-out may also be formed in the intermediate layer81.

Since the intermediate layer 81 is light-reflecting as well astranslucent, the exposure of relatively narrow portions of theintermediate layer in the construction shown in Figure 5, provides thedesired relatively narrow design elements for observation by reliectedlight. The same design elements arevisible, however, bytransillumination and the local convex offset 93 of the material of theinner or back layer 80 provides a local lens effect that greatlyimproves the lighting of the narrow design elements bytransillumination.

From the foregoing description, it is clear that the first design ofrelatively wide markings is provided by the design construction andfabrication procedure illustrated by Figure 4, and that the accompanyingsecond design of relatively narrow markings is provided by the designconstruction and method of fabrication illustrated by Figure 5.

If desired, the relatively wide design elements on the` panel P may beprovided by a construction and method of fabrication illustrated byFigure 6'. YIn this modified practice of the invention, the step ofsubjecting the 3-ply thermoplastic plates to heat and pressure in asuitable mold is used not only to provide a relief pattern for thenarrow design elements, but also to provide a relief pattern for thewider design elements.

In Figure 6, which corresponds to Figure 4, the relatively wide designelement comprising the wide line in Figure l, is provided by firstforming the relatively wide design elements in relief as indicated bythe dotted line 95. The relief design of relatively wide elements isthen shaved away flush with the normal outer surface of the outer opaquelayer 82. In this instance, the degree of protrusion of the 3plymaterial to provide the relief design is relatively great so that whenthe relief design is shaved away, cut-outs are formed in both layers 81and 82 as may be seen in Figure 6. An outer layer 96 oflight-translucent material is then applied to the surface of the 3plyplate to cover the cut-outs, the outer layer having the width desiredfor visibility by reflected light. One advantage of this secondprocedure for providing the relatively wide design elements is that thematerial of the back layer 80 is formed with a local con- Vex offset 97that is more pronounced than the offset 93 in Figure 5 and thereforeresults in a more effective lens effect for improving thetransillumination of the wide design elements.

` It will be noted in Figure 6, as well as in Figure 4, that the outerlayer that is added to provide a relatively wide design element forobservation by reflected light, stands out from the plane of the outersurface of the outer opaque layer 82 and therefore is more readilyvisible at relatively low angles with respect to the surface of thepanel than prior art markings which are ush with the outer surface.

It is not necessary in the procedure illustrated by Fig- -ure 6, to makethe relief protrusion so pronounced that cut-outs are formed in theintermediate layer 81. If desired, the relief may be less pronounced sothat the intermediate layer 81 will be merely skimmed in the shavingprocess, instead of completely penetrated.

My description in specific detail of preferred practices of theinvention, by Way of example and to illustrate the principles involved,will suggest various changes, substitutions and other departures from mydisclosure that properly lie within the spirit and scope of the appendedclaims.

I claim:

l. A method of fabricating a panel having a design thereon visible byboth reflected light and by light transmitted through the material ofthe panel, including the steps of: forming a unitary laminated plate ofplastic material having a relatively thick inner light-transmittinglayer and an outer relatively thin, substantially opaque layer with saidouter layer having cut-outs of the pattern of said design; andsuperimposing on said laminated plate a layer of light-reflecting,translucent material of the pattern Of said design, the superimposedpattern being applied to the cut-out pattern and the elements of thesuperimposed pattern being made wider than the corresponding elements ofthe cut-out pattern.

2. A method of Ifabricating a panel having a design thereon visible byboth reflected light and by light transmitted through the material ofthe panel, including the steps of: forming a unitary laminated plate ofthermoplastic material having a relatively thick inner lighttransmittinglayer, an intermediate, relatively thin, translucent layer, and an outerrelatively thin, substantially opaque layer; removing portions of saidintermediate and outer layers to form cut-outs therein of the pattern ofsaid design; and applying light-reflecting translucent material to saidcut-outs and to adjacent portions of the face of said outer layer toform an additional layer conforming to the pattern of said design withthe elements of the applied design wider than the corresponding elementsof the cut-out design.

3. A method of fabricating a panel having a design thereon visible byboth reflected light and by light transmitted through the material ofthe panel, including the steps of: forming la unitary laminated plate ofplasticmaterial having a relatively thick inner light-transmitting layerand an outer relatively thin, substantially opaque layer; engraving saidplate through said outer layer into said inner layer to form groovesconforming to the pattern of said design; and applying alight-reflecting translucent material to cover said grooves and to coveradjacent portions of the outer surface of said outer layer to form asuperimposed pattern of said design with the elements of thesuperimposed design wider than the corresponding elements of the groovepattern and with the superimposed pattern of material protruding fromthe outer surface of said unitary plate.

4. A method of fabricating a panel having a design' thereon visible byboth reflected light and by light transmitted through the material ofthe panel, including the steps of: forming a unitary laminated plate ofthermoplastic material having a relatively thick inner lighttransmittinglayer, an intermediate relatively thin translucent layer and an outerrelatively thin, substantially opaque layer; subjecting said unitaryplate to heat and; pressure to displace selected portions of the plateoutward from the outer face of the plate to form a relief patternconforming to said design, with the full thickness of both saidintermediate layer and said outer layer extending through the plane ofthe outer face of the plate into the relief pattern; removing thematerial of said relief pattern thereby forming a similar pattern ofcut-outs in said intermediate and outer layers; and applying alight-reflecting translucent material to said cut-outs and to adjacentportions of the face of said outer layer to form an additional layerconforming to the pattern of said design, with the elements of theapplied design Wider than the corresponding elements of the cut-outdes1gn.

5. A method of fabricating a panel having a first design thereon ofrelatively wide design elements and having a second design thereon ofrelatively narrow design elements, said two designs being visible bothby reflected light and by light transmitted through the material of thepanel, said method including the steps of forming a unitary laminatedplate of thermoplastic material having a relatively thick innerlight-transmitting layer, and intermediate relatively thin, translucentlayer, and an outer' relatively thin, substantially opaque layer;engraving said plate through said outer and intermediate layers to formgrooves conforming to the pattern of said first design; applying alight-reflecting translucent material to said grooves and to coveradjacent portions of the outer surface of said outer layer to form asuperimposed pattern of said first design with the elements of thesuperimposed pattern wider than the corresponding elements of the groovepattern and with the superimposed pattern of material protruding fromthe outer surface of said unitary plate; applying heat and pressure todisplace narrow portions of the plate outward from the plane of theouter surface of said outer opaque layer to form a relief patternconforming to said second design; and removing material from said reliefpattern to expose the portions of the material of said intermediatelayer conforming to said second design.

6. A panel of the character described having a designV thereon forobservation either by reflected light or by light transmitted throughthe material of the panel, comprising: Va unitary laminated plate ofplastic material having an inner relatively thick layer oflight-transmitting material and an outer relatively thin layer of opaquematerial, said opaque layer having cut-outs therein conforming to saiddesign; and an additional layer of lightreflecting translucent materialconforming to said design, said additional layer covering said cut-outsand extending over adjacent portions of said opaque layer whereby theelements of the design formed` by said additional layer are wider thanthe corresponding elements of the design formed by said cut-outs, andwhereby the wider elements protrude from the plane of the outer surfaceof said opaque layer.

7. A panel as set forth in claim 6, in which the material of saidlight-transmitting layer extends through said cut-outs to the plane ofthe outer surface of said outer opaque layer.

8. A panel as set forth in claim 6, in which said inner layer hasrecesses registered with said cut-outs and in which said vadded layerextends into said cut-outs and into said recesses.

9. A panel as set forth in claim 8 in which said recesses are of curvedcross-sectional configuration at the bottom corners thereof.

References Cited in the le of this patent UNITED STATES PATENTS1,513,259 Miyata Oct. 28, 1924 1,781,727 Knechtel Nov. 18, 19302,072,439 Andres Mar. 2, 1937 2,262,930 Gasper Nov. 18, 1941 2,594,081Shlenker Apr. 22, 1952 2,595,973 Nevgass May 6, 1952 2,602,036 SullivanJuly 1, 1952

